Wet sprinkler system
These systems are installed in premises where there is no possibility of pipes freezing. The system pipework is charged with water under pressure at all times. When a sprinkler head is activated by the heat from a fire water flows immediately on to the seat of the fire.
Dry sprinkler system
Dry pipe systems are installed in premises where there is a possibility of water in pipes freezing. Dry systems are charged with compressed air or another inert gas i.e. nitrogen. When a fire sprinkler head is activated by the heat from a fire, the air pressure drops and the valve opens allowing water to fill the pipes and discharge from the sprinklers on to the seat of the fire.
Pre-Action sprinkler system
Pre-action systems are commonly installed in areas where the accidental discharge of water may be problematic i.e. when a sprinkler head is accidently damaged.
They are installed in areas such as data processing facilities, document storage or cold storage warehouses. The system can only be activated by a combination of events i.e. operation of a smoke/heat detection system AND the operation of a sprinkler in a fire condition. The pipes are normally filled with compressed air and water is only allowed to fill the pipes when the smoke/heat detection system is activated. This ensures that accidental discharge will not occur. Three are several modes of operation and these can be setup in the sophisticated system control panel to suit the client’s exact requirements.